WO2012119649A1

WO2012119649A1 - System and method for image-guided radio therapy

Info

Publication number: WO2012119649A1
Application number: PCT/EP2011/053529
Authority: WO
Inventors: Peter Fröberg; Rui Chen
Original assignee: Elekta AB
Current assignee: Elekta AB
Priority date: 2011-03-09
Filing date: 2011-03-09
Publication date: 2012-09-13
Anticipated expiration: 2013-09-09

Abstract

The present invention relates to the field of radiation therapy. In particular, the invention relates to systems and methods for image guided therapy, such as radiotherapy. According to the invention, the therapeutic apparatus and the image recording device are tracked and a relative position data for the therapeutic apparatus relative the image recording device is determined. The patient position data of the anatomy of said patient is extracted and a three-dimensional reference image of the patient is created. Further, images of said therapeutic apparatus are continuously using an image recording device. The three-dimensional reference image is super- positioned the recorded images and are displayed, wherein a user is provided with guidance when positioning a patient relative said therapeutic apparatus for treatment session.

Description

SYSTEM AND METHOD FOR IMAGE-GUIDED RADIO THERAPY

Field of the invention

The present invention relates to the field of radiation therapy. In particular, the invention relates to systems and methods for image guided therapy, such as radiotherapy.

Background of the invention

The development of surgical techniques has made great progress over the years. For instance, for patients requiring brain surgery, non-invasive surgery is now available which is afflicted with very little trauma to the patient.

Stereotactic radiation surgery is such a minimally invasive treatment modality that allows delivery of a large single dose of radiation to a specific intracranial target while sparing surrounding tissue. Unlike conventional fractionated radiation therapy, stereotactic radiation surgery does not rely on, or exploit, the higher radiation sensitivity of neoplastic lesions relative to normal brain (therapeutic ratio). Its selective destruction depends primarily on sharply focused high-dose radiation and a steep dose gradient away from the defined target. The biological effect is irreparable cellular damage and delayed vascular occlusion within the high-dose target volume. Because a therapeutic ratio is not required, traditionally radiation resistant lesions can be treated. Because destructive doses are used, however, any normal structure included in the target volume is subject to damage.

One such non-invasive radiation therapy technique is so called LINAC (Linear Accelerator) radio therapy or radiation therapy. In a LINAC radiation therapy system, a collimated x-ray beam of a very high energy level is focused on a stereotactically identified intracranial target. In such an accelerator, electrons are accelerated to near light speed and are collided with a heavy metal, e.g. tungsten. The collision mainly produces heat but a small percentage of the energy is converted into highly energetic photons, which, because they are electrically produced, are called "x-rays". The gantry of the LINAC rotates around the patient, producing an arc of radiation focused on the target. The couch in which the patient rests is then rotated in the horizontal plane, and another arc is performed. In this manner, multiple non- coplanar arcs of radiation intersect at the target volume and produce a high target dose, resulting in a minimal radiation affecting the surrounding brain.

Another system for non-invasive surgery is sold under the name of Leksell Gamma Knife^®, which provides such surgery by means of gamma radiation. The radiation is emitted from a large number of fixed radioactive sources and is focused by means of collimators, i.e. passages or channels for obtaining a beam of limited cross section, towards a defined target or treatment volume. Each of the sources provides a dose of gamma radiation which is insufficient to damage intervening tissue. However, tissue destruction occurs where the radiation beams from all radiation sources intersect or converge, causing the radiation to reach tissue-destructive levels. The point of convergence is hereinafter referred to as the "focus point". Such a gamma radiation device is, for example, referred to and described in US 4,780,898.

In the system, the head of a patient conventionally is immobilized in a stereotactic instrument which defines the location of the treatment volume in the head. Further, the patient is secured in a patient positioning unit which moves the entire patient so as to position the treatment volume in coincidence with the focus point of the radiation unit of the radiation therapy system.

Consequently, in radiation therapy systems, such as a LINAC system or a Leksell Gamma Knife^® system, it is of a high importance that the positioning unit which moves the patient so as to position the treatment volume in coincidence with the focus point of the radiation unit of the system is accurate and reliable. That is, the positioning unit must be capable of position the treatment volume in coincidence with the focus point at a very high precision. This high precision must also be maintained over time. In order to further reduce potential damage of healthy tissue, medical

procedures performed by means of a LINAC system or a Leksell Gamma Knife^® system often involve repeated treatment at different times so called fractionated therapy. A routine course of radiation therapy may span from 2 fractions up to a large number of fractions, for example, 50 - 100 fractions over a period from 2 days to several weeks. The number of treatments depends on the specifics of the particular disease. For each fraction the patient must be repositioned at the radiation therapy unit and aligned relative to the radiation beam or beams at a highly precise degree of accuracy.

Hence, in order to obtain as favourable clinical effect as possible during the therapy is it of an utmost importance that the radiation reaches and hits the target, i.e. the treatment volume, with a high precision and thereby spares the healthy tissue being adjacent to and/or surrounding the treatment volume. To achieve this, the patient is according to conventional technology immobilized during each therapy session and, moreover, the position of the head of the patient must be exactly the same in each therapy session as in the reference position, i.e. the position during the session when the images to create the therapy plan were captured by means of, for example,

Computerized Tomography Imaging (CT-imaging).

Consequently, in fractionated radiation therapy where the patient is docked in and out of the radiation therapy system at each therapy session, it must be secured that the patient is positioned in exactly the same position and orientation relative the radiation beam or beams as in the session when the images were captured to create the therapy plan and in exactly same position as in the preceding therapy sessions.

One prior art method for enabling measurements of the head of a patient and for immobilizing or fixating the head of the patient during neurological diagnosis, therapy or surgery, in particular during radiation therapy relatively an interface unit, includes using a stereotactic frame provided with pin support members in form of posts having fixation pins for invasive fixation to the skull of a patient. This kind of frame is not suitable for fractionated therapy.

A prior art method more suitable for positioning a patient relative a therapeutic apparatus in connection with fractionated therapy involves mouth pieces or bite-block shaped after upper palate of the patient and is thus adapted to be received in the mouth of the patient, i.e. containing an impression of the teeth of the patient, and support structure and the stereotactic frame for connecting the mouth-piece or bite block with the therapy unit. When positioning the patient, the patient is placed on the treatment couch or bed and is positioned such that the patient can receive the bite-block in the mouth and thereafter the patient is positioned in the treatment position.

Another prior art method used for positioning a patient relative a therapeutic apparatus in connection with fractionated therapy uses a mask shaped after the head or face of the patient. The mask is connected to a support structure and the stereotactic frame for connecting the mask with the therapy unit. The principle of this method is the same as the method using a bite-block. The patient is placed on the treatment couch or bed and is positioned such that the mask thereafter can be fitted on the head or face of the patient and the patient is assumed to be positioned in the treatment position.

Further prior art method include positioning the patient on the treatment couch or treatment bed in the treatment position, or the supposed treatment position, and thereafter bracing the patient against the treatment couch or bed to keep the patient in the treatment position.

However, there are weaknesses associated with the use of the prior art methods. For example, the prior art methods may not provide the high degree of reproducibility required in many therapeutic applications, such as e.g.

radiation therapy, due to, for example, mechanical instability in case of the bite-block and the mask and due to, for example, inaccuracy in the positioning of the patient relative the treatment couch or bed.

Hence, there is a need within the art of improved methods and systems that provide positional reproducibility with a high degree of accuracy.

Summary of the invention

An object of the present invention is to provide improved methods and systems that provide positional reproducibility with a high degree of accuracy in treatments of patients, such as e.g. radiotherapy.

Another object of the present invention is to provide improved methods and systems for providing assistance to a surgeon when positioning a patient in connection with fractionated therapy, such as fractionated radiotherapy. A further object of the present invention is to provide image-guidance methods and systems for positioning a patient in connection with fractionated treatment of patients, for example, fractionated radiotherapy.

Yet another object of the present invention is to provide image- guidance methods and systems for positioning a patient in connection with fractionated treatment of patients, such as e.g. fractionated radiotherapy, based on augmented reality.

Hence, the objects of the present invention are to provide an image- guidance method and system based on augmented reality for a therapeutic apparatus, such as an irradiation unit, suitable for non-invasive irradiation treatment of conditions such as cancerous lesions in the brain, eye, head and neck regions. The image-guidance for locational accuracy provided by the present invention can be used as a complement or alternative to a mask or bite-block or other tools for providing positioning accuracy. The incorporation of an image-guidance system and method into an irradiation routine would therefore allow inter alia for more accurate localization of the target (within the patient) throughout the treatment process.

The present invention may be used in a Leksell Gamma Knife^® system and other radiation therapy systems such as the LINAC system where fractionated therapy is common as well as in systems for MEG

(magnetoencephalography) therapy. Furthermore, the present invention may be used in other medical procedures or medical therapies outside

radiotherapy where a need for repeat and accurate positioning of a patient or a portion of a patient exists such as where a first medical procedure is performed requiring a precise location of the patient or portions of the patient and, at some later point in time, a second medical procedure is performed on the patient where a precise location of the patient or portions of the patient is required. It might be possible to repeat laborious and time-consuming localizations steps for the second medical procedure at the expense of increased medical costs and complexity. As used herein, the term "medical procedure" is a procedure for diagnostic and/or remedial purposes. The above stated objects as well as others are fulfilled by the present invention as defined by the independent claims. Preferred embodiments are defined by the dependent claims.

According to an aspect of the present invention, there is provided a system for projecting a three-dimensional image of a patient anatomy relative a therapeutic apparatus using augmented reality. The system comprises a tracking and monitoring device configured to: monitor the therapeutic apparatus and provide therapeutic apparatus position data, the therapeutic apparatus position data describing a position of the therapeutic apparatus in six dimensions relative the tracking and monitoring device; and to track an image recording device and providing image recording device position data, the image recording device position data describing a position of the image recording device in six dimension relative the tracking and monitoring device. An image recording device is configured to record images of the therapeutic apparatus or a part of the therapeutic apparatus, the images including at least the portion of the patient including the part being a subject for therapy. A processing unit is configured to:

extract position data of the anatomy of the patient from the therapeutic apparatus, the position data defining a predetermined treatment position of the patient on a treatment surface for a therapy session relative the

therapeutic apparatus;

create a three-dimensional reference image of the patient using the extracted patient position data;

super-position the three-dimensional reference image of the patient on the treatment surface, the three-dimensional reference image being positioned in the predetermined treatment position relative the therapeutic apparatus; and

synchronize the super-positioned three-dimensional reference image and the recorded images using relative position data defining a relative position of the therapeutic apparatus to the image recording device.

A display device is configured to display the synchronized images, wherein a user can be provided with guidance when positioning a patient relative the therapeutic apparatus for treatment session. According to an embodiment of the system aspect of the invention, the processing unit comprises a patient position data extraction module

configured to extract position data of the anatomy of the patient from the therapeutic apparatus, the position data defining a predetermined treatment position of the patient on a treatment surface for a therapy session relative the therapeutic apparatus. The processing unit further comprises a reference image creating module configured to create a three-dimensional reference image of the patient using the extracted patient position data and an image super-position module configured to super-position the three-dimensional reference image of the patient on the treatment surface, the three- dimensional reference image being positioned in the predetermined treatment position relative the therapeutic apparatus. Moreover, the processing unit includes an image synchronizing module configured to synchronize the super- positioned three-dimensional reference image and the recorded images using relative position data defining a relative position of the therapeutic apparatus to the image recording device.

According to a second aspect of the present invention, there is provided a method for projecting a three-dimensional image of a patient anatomy relative a therapeutic apparatus using augmented reality. The method comprises creating the projection of the patient anatomy based on patient position data defining a predetermined treatment position relative the therapeutic apparatus, wherein the three-dimensional projection is used as a reference position of the patient, obtaining a video-feed including at least a part of the therapeutic apparatus and the patient and superimposing the projection on the video-feed to display the projection and the patient.

According to an embodiment of the second aspect, the method comprises monitoring the therapeutic apparatus or a part of the therapeutic apparatus delivering therapy such as a radiation dose delivery unit or another part having a known position relative the radiation dose delivery unit using a tracking and monitoring device and providing therapeutic apparatus position data, the therapeutic apparatus position data describing a position of the therapeutic apparatus in six dimensions relative the tracking and monitoring device and tracking an image recording device using the tracking and monitoring device and providing image recording device position data, the image recording device position data describing a position of the image recording device in six dimension relative the tracking and monitoring device. Further, relative position data is determined for the therapeutic apparatus relative the image recording device. Patient position data of the anatomy of the patient is extracted defining a predetermined treatment position of the patient on a treatment surface for a therapy session relative the therapeutic apparatus and a three-dimensional reference image of the patient using the extracted patient position data is created.

Moreover, images of the therapeutic apparatus is recorded using the image recording device, the images including at least the portion of the patient including the part being a subject for therapy and the three- dimensional reference image of the patient is super-positioned on the treatment surface, the three-dimensional reference image being positioned in the predetermined treatment position relative the treatment apparatus.

Thereafter, the super-positioned three-dimensional reference image and the recorded images are synchronized using the relative position data and the synchronized images are displayed, wherein a user is provided with guidance when positioning a patient relative the therapeutic apparatus for treatment session.

The present invention is based on the idea of using augmented reality to project a 3D image of the patient anatomy in the desired treatment position, which projection can be used as a reference by a surgeon to position the patient for a therapy session. The physician or surgeon is thus guided when positioning the patient by a displayed reference image of the part of the patient to be treated, e.g. the head, super-positioned over a video feed of the patient. According to the present invention, a description of the patient anatomy, i.e. skull shape, defined from MR or CT images in a treatment planning system in relation to a given dose distribution is extracted and used as basis for creating the 3D super-positioned reference image. The correct position of the patient anatomy (i.e. the position of the patient when the target within the patient to be irradiated is positioned in the correct position relative the therapeutic apparatus) is super-positioned on the treatment surface using augmented reality allowing the surgeon to see the correct patient position on a display. During planning the target is defined relative the patient anatomy and information about the position of the patient geometry relative the radiation dose is defined in six dimensions. As the dose delivery system (e.g. a radiation unit in the Perfexion system) has a known position relative the radiation, the dose delivery system and the patient geometry both have known positions relative the planned target. Based on this information, the geometry of the patient when perfectly positioned can be calculated relative the dose delivery system. This will be a position in the centre of the dose delivery system (i.e. inside the radiation unit). Further, the position of the patient positioning system when the dose delivery is initiated is known as well as the position of the patient positioning system when the patient is

positioned. The inverse of the difference between these two positions can be added to the position of the patient geometry in the treatment position, which translates it out from the dose delivery system to where the patient is located.

According to the present invention, a tracking and monitoring device, e.g. video camera or IR camera including a IR light emitter, is included to track the therapeutic apparatus or a part of the therapeutic apparatus delivering therapy such as a radiation dose delivery unit or another part having a known position relative the radiation dose delivery unit and the image recording apparatus, which provides images of the patient. Further, a marker (at least one and preferably at least three) is preferably arranged to be mounted on the therapeutic apparatus or in the vicinity and the marker arranged to define its position in 6D. The tracking and monitoring device may be an ultra-sound tracking and monitoring device, an electromagnetic tracking and monitoring device or an optical tracking and monitoring device. Examples of optical tracking and monitoring devices include tracking based on computer vision or infra-red (IR) tracking. In a system based on computer vision, only one marker and one video-camera are required. The same video-camera can be used to capture live feed of the patient as for monitoring the therapeutic apparatus. This system requires a clear sight line between the video-camera and the patient as well the video-camera and the therapeutic apparatus. An alternative embodiment is IR based tracking and monitoring in which case both the therapeutic apparatus and the video-camera have to be provided with markers, for example, reflecting units capable of reflecting IR light. In this case, no clear line of sight is required between the marker on the patient and the video-camera. However, a clear line of sight is required between the markers and the IR tracking and monitoring device (e.g. at least one IR camera). Thus, the IR based system includes markers (at least three), a video-camera and at least one IR camera (it is however conceivable to use a video-camera also capable of recording IR light given that at least one IR emitted also is included into the system). At least three markers are needed for the video-camera as well for the therapeutic apparatus or a part of the therapeutic apparatus delivering therapy such as a radiation dose delivery unit or another part having a known position relative the radiation dose delivery unit must be monitored in order to super-position the 3D

reconstruction of the patient anatomy in the right place in the video feed.

As the skilled person realizes, steps of the methods according to the present invention, as well as preferred embodiments thereof, are suitable to realize as computer program or as a computer readable medium.

Further objects and advantages of the present invention will be discussed below by means of exemplifying embodiments.

Brief description of the drawings

Fig. 1 is a perspective view of a therapeutic apparatus in which the present invention can be used to position a patient in connection with a therapy session.

Fig. 2 is a schematic view of an embodiment of a system in

accordance with the present invention;

Fig. 3 is a schematic view of an embodiment of a system in

accordance with the present invention;

Fig. 4 is a flow chart describing the overall steps of the method according to the present invention.

Fig. 5 is a flow chart describing steps of an embodiment of a method according to the present invention. Detailed description of the drawings

According to objects of the present invention, a patient positioning guidance system based on augmented reality is provided that can be integrated with, or used in co-operation with, a therapeutic apparatus such as an irradiation unit or a MEG (magnetoencephalography) apparatus for providing aid or guidance to and assisting medical personnel in positioning a patient in connection with fractionated treatment sessions.

With reference first to Fig. 1 , an exemplary radiation therapy device, e.g. a Leksell Gamma Knife^® system, in which the patient positioning guidance system according to the present invention can be used in

connection with treatment of a patient will be described.

However, as will be appreciated from the following detailed description, the present invention may also be used in other radiation therapy systems such as the LINAC system where fractionated therapy is common.

Furthermore, the present invention may be used in other medical procedures or medical therapies outside radiotherapy where a need for repeat and accurate positioning of a patient or a portion of a patient exists such as where a first medical procedure is performed requiring a precise location of the patient or portions of the patient and, at some later point in time, a second medical procedure is performed on the patient where a precise location of the patient or portions of the patient is required. It might be possible to repeat laborious and time-consuming localizations steps for the second medical procedure at the expense of increased medical costs and complexity. As used herein, the term "medical procedure" is a procedure for diagnostic and/or remedial purposes.

The radiation therapy system comprises a radiation therapy unit or therapeutic apparatus 10 and a patient positioning unit 20 will be described. Using the patient positioning unit 20, the patient can be positioned relative the radiation unit. The patient positioning guidance system 50 (see Fig. 2 and 3) according to the present invention is used for providing guidance or aid to the medical personnel when positioning the patient. In the therapeutic apparatus 10, there are provided radioactive sources, radioactive source holders, a collinnator body, and external shielding elements. The collimator body comprises a large number of collimator channels directed towards a common focus point, in a manner as is commonly known in the art.

The collimator body also acts as a radiation shield preventing radiation from reaching the patient other than through the collimator channels.

Examples of collimator arrangements in radiation therapy systems applicable to the present invention can be found in US Patent No. 6,931 ,096 , which is hereby incorporated herein by reference in its entirety. However, the present invention is also applicable to radiation therapy systems using other arrangements for collimating radiation into a fixed focus point, such as is disclosed in US Patent No. 4,780,898. Furthermore, the patient positioning guidance system according to the present invention is also applicable to LINAC radiosurgical systems, in which a collimated x-ray beam is focused on a stereotactically identified intracranial target and the gantry of the LINAC rotates around the patient, producing an arc of radiation focused on the target.

The patient positioning unit 20 comprises a rigid framework 22, a slidable or movable carriage 24, and motors (not shown) for moving the carriage 24 in relation to the framework 22. The carriage 24 is further provided with a patient bed 26 for carrying and moving the entire patient.

Conventionally, during a therapy session, the patient head is fixed relative the therapy system via a fixation unit and a stereotactic head frame, which comprises engagement points adapted for engagement with the engagement points 30, 32 of the radiation therapy system. For example, a bite-block shaped after upper palate of the patient, i.e. containing an impression of the teeth of the patient, and thus adapted to be received in the mouth of the patient is connected to the support structure or the stereotactic frame. During a therapy session, the patient bites the bite-block and the bite- block is fixated to the upper palate of the patient by means of a low pressure or vacuum pump device connected to the mouth-piece via tubings. Further, the mouth-piece or bite-block is adapted to be fixated relatively the support structure and stereotactic frame and, thus, relatively the therapy unit. During movement of the treatment volume in the head of the patient in relation to the radiation focus point, along the three orthogonal axes x, y, and z shown in Fig. 1 , the entire patient is moved along the axes. Thus, there is no relative movement between the head frame and the carriage 24 of the patient positioning unit 20.

The present invention is instead based on the idea of using augmented reality to project a 3D image of the patient anatomy in the desired position for guiding and providing guidance to the medical personnel, e.g. the surgeon, when positioning the patient for treatment, for example, in combination with a bite-block or as an alternative to a bite-block.

With reference to Fig. 2, a patient positioning guidance system 50 according to embodiments of the present invention will be discussed.

Communication within the system 50, for example, between different units, devices and modules is indicated with arrows in Fig. 2, which communication e.g. may be wireless or via wires.

A tracking and monitoring device 52 is configured to monitor the therapeutic apparatus 10 and to provide therapeutic apparatus position data, DatajApos., defining a position of the therapeutic apparatus 10 in six

dimensions relative the tracking and monitoring device 52. The six

dimensions are translations in the three directions x, y, and z, respectively, and rotation around the x-axis, y-axis, and z-axis, respectively.

Furthermore, the tracking and monitoring device 52 is configured to track an image recording device 54 and provide image recording device position data, Datai_RDP0S., defining a position of the image recording device 54 in six dimensions relative the tracking and monitoring device 52.

According to this embodiment of the present invention, an infra-red (IR) tracking and monitoring device 52 is used including at least one IR light source 51 configured to emit IR light and a IR detector 53 configured to receive reflected IR light and to provide output signals corresponding to the received IR light. A first reflector unit or marker unit 55 is provided on the therapeutic apparatus 10 to reflect the emitted IR light from the tracking and monitoring device 52. Preferably, at least three IR reflectors are included in the reflector unit which reflectors are not arranged according to straight line. Further, a second reflector unit or marker unit 57 is provided on the image recording unit 54. Hence, the IR tracking and monitoring device 52 is configured to receive and capture the reflected IR light from the reflectors 55 and 57 at the IR detector 53 of the IR tracking and monitoring device 52 and to determine the six dimensional position data for the therapeutic apparatus 10 and image recording device 54, respectively, relative the tracking and monitoring device 52 based on the captured IR light. The determination of the six dimensional position data for the therapeutic apparatus 10 and image recording device 54, respectively, relative the tracking and monitoring device 52 may be performed using technique known within the art.

According to another embodiment, the infra-red tracking and monitoring device comprises both an infra-red tracking and monitoring device and an image recording device. For example, it is possible to use a video- camera capable of recording IR Iight.

Another optical system may be based on computer vision. In this embodiment of the present invention, the image capturing device also functions as tracking and monitoring device tracking at least one visual marker.

According to alternative embodiments of the present invention, ultrasound tracking or electromagnetic tracking and monitoring devices may be used.

An image recording device is configured to record images of the therapeutic apparatus 10. In this embodiment, a digital video camera is used to repeatedly record images of the therapeutic apparatus. The frame rate of the video camera is preferably capable of feeding real time images to the tracking and monitoring device 52 or to a processing unit 56 (e.g. a personal computer). The video camera 54 is positioned such that a recorded scene includes at least the portion of the patient including the part being a subject for therapy when the patient is positioned in the therapeutic apparatus 10 for a therapy session.

The processing unit 56 is configured to communicate with the tracking and monitoring device 52 and to the therapeutic apparatus 10 and the image recording device 54. The modules of the processing unit 56 described below may, for example, be implemented as hardware modules (including

specialized circuits such as discrete logic gates interconnected to perform a specialized function or application-specific integrated circuits) or software modules comprising program instructions executed by one or more

processors, or a combination thereof. Moreover, the modules of the

processing unit can additionally be considered to be embodied entirely within any form of computer-readable storage medium having stored therein an appropriate set of instructions for use by or in connection with an instruction- execution system, apparatus or device, such as a computer-based system, processors containing system or other system that can fetch instructions from a medium and execute the instructions. As used herein, a "computer- readable" can be any means that contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction- execution system, apparatus or device. The computer-readable medium can be, for example, but not limited to, an electronic, magnetic, electromagnetic, infrared, or semiconductor system, apparatus, device or propagation medium. More specific examples (a non-exhaustive list) of the computer-readable medium include an electrical connection having one or more wires, a portable computer diskette, a random access memory (RAM), a read only memory (ROM), an erasable programmable read only memory (EPROM or flash memory), an optical fibre, and a portable compact disc read only memory (CD-ROM).

In this embodiment of the present invention the processing unit 56 comprises a patient position data extraction module 58 configured to extract patient position data of the anatomy of the patient from the therapeutic apparatus 10. The position data defines a predetermined treatment position of the patient on the patient bed 26 for a therapy session relative the therapeutic apparatus 10. This predetermined treatment position is thus the position of the patient during the treatment session and the user of the system, e.g. a physician, accordingly strives to position as close as possible to this predetermined treatment position. The processing unit 56 further comprises a relative position data calculation module 59 configured to calculate relative position data, Data(TA rei. icDjpos., defining the position of the therapeutic apparatus 10 relative the image recording device 54 in the six dimensions based on the therapeutic apparatus position data, DataiApos_., and the image recording device position data, DataiRDpos.-

Further, the processing unit 56 comprises a reference image creating module 60 configured to create a three-dimensional reference image of the patient using the extracted patient position data. An image super-position module 62 of the processing unit 56 is configured to super-position the three- dimensional reference image of the patient on the patient bed 26, which three-dimensional reference image is positioned in the predetermined treatment position relative the therapeutic apparatus 10. Moreover, the processing unit 56 includes an image synchronizing module 64 configured to synchronize the super-positioned three-dimensional reference image and the recorded images using the relative position data, Data(TA rei. ICD)_P

A display device 66 is configured to display the synchronized images, for example, a display device of a personal computer to thereby present the images for a user 70, for example, a physician performing the therapy. The user 70 is hence guided by the displayed reference image of the patient anatomy when positioning the patient since the patient^'s current position also is displayed. By comparing the current position of the patient (i.e. the displayed image of the patient) and the super-positioned 3D reference image of the patient anatomy, the surgeon is provided with feed-back in real-time of a current patient position relative the reference image during the patient positioning procedure.

According to an embodiment of the present invention, the display device 82 is arranged in a pair of eye glasses 80 having a head mounted display or a heads-up display; see Fig. 3, which the user (user not shown in Fig. 3) may wear during a procedure for positioning the patient. The display device 82 may be complemented by the display device 66 arranged, for example, in a personal computer. The pair of eye glasses 80 may further include a video camera 84 for recording images of the therapeutic apparatus 10 and a communication module 86 for communicating with the processing unit 56 wirelessly, e.g. a Bluetooth module. Furthermore, at least one marker 88 is arranged on the eye glasses 80. In one embodiment, three IR reflectors 88 for enabling tracking of the user and the video camera 84 by the IR tracking and monitoring device 52 are arranged on the eye glasses 80.

With reference now to Fig. 4, the overall steps of the method according to the present invention are discussed. According to the present invention, augmented reality is used to project a 3D image of the patient anatomy in the desired treatment position, which projection can be used as a reference by a physician or surgeon to position the patient for a therapy session. The physician or surgeon is thus guided when positioning the patient by a displayed reference image of the part of the patient to be treated, e.g. the head, super-positioned over a video feed of the patient.

First, at step S90, a projection of the patient anatomy is created based on patient position data defining a predetermined treatment position relative the therapeutic apparatus, wherein the three-dimensional projection is used as a reference position of the patient.

At step S92, a video-feed including at least a part of the therapeutic apparatus and the patient is obtained.

Thereafter, at step S94, the projection is superimposed on the video- feed to display the projection and the patient. The physician or surgeon is thereby capable of positioning the patient in the treatment position using the super-positioned three-dimensional reference image as a guide. When the patient is aligned with the three-dimensional reference image, the patient is located in the correct treatment position.Turning now to Fig. 5, the steps of an embodiment of the method according to the present invention will be discussed.

The method described below is, for example, executed in connection with positioning a patient in preparation for therapy, for example, a

radiotherapy or radiosurgery session. According to the present invention, a three-dimensional image of the patient anatomy in the correct treatment position is projected on a display using augmented reality and superimposed a video-feed of the therapeutic apparatus and the patient, which can guide the physician or surgeon when positioning the patient for the treatment.

First, at step S100, the therapeutic apparatus 10 is monitored using the tracking and monitoring device 52 and therapeutic apparatus position data is provided. The therapeutic apparatus position data, DataiApos., defines a position of the therapeutic apparatus 10 in six dimensions relative the tracking and monitoring device 52.

The six dimensions are translation in the three directions x, y, and z, respectively, and rotation around the x-axis, y-axis, and z-axis, respectively.

At step S1 10, the image recording device 54, 84 is tracked by the tracking and monitoring device 52 and image recording device position data is provided. The image recording device position data, DataiRD_P0S., defines a position of the image recording device 54 in six dimension relative the tracking and monitoring device 52.

It should be noted that step S100 and S1 10 can be executed in reversed order or simultaneously.

Preferably, the therapeutic apparatus position data and image recording device position data is synchronized in time, for example, by simultaneous tracking or by processing the data to obtain the synchronizing.

Thereafter, at step S120, relative position data, Data(TA rei. ICD)_P defining the position of the therapeutic apparatus 10 relative the image recording device 54 in the six dimensions, is determined or calculated based on the therapeutic apparatus position data, DataiApos., and the image recording device position data, DataiRD_P0S.- At step S130, patient position data of the anatomy of the patient is extracted, for example, from the therapeutic apparatus 10, which patient position data defines a predetermined treatment position of the patient on a treatment surface, e.g. the patient 26, for a therapy session relative the therapeutic apparatus 10. This predetermined treatment position is thus the position of the patient during the treatment session and the user of the system, e.g. a physician, accordingly strives to position as close as possible to this predetermined treatment position. It should be noted, that step S130 can be executed, for example, before steps S100 - S120, or after step S100 and S1 10 but before step S120.

At step S140, images of therapeutic apparatus 10 is recorded by the image recording device 54,84, which images include at least the portion of the patient including the part being a subject for therapy.

At step S150, a three-dimensional reference image of the patient is created using the extracted patient position data. It should be noted that this step (i.e. step S150) instead could be performed after step S130 and thus before the step of recording images of the therapeutic apparatus 10.

Thereafter, at step S160, the three-dimensional reference image of the patient is super-positioned on the treatment surface, the three- dimensional reference image being positioned in the predetermined treatment position relative the therapeutic apparatus.

At step S170, the super-positioned three-dimensional reference image and the recorded images are synchronized using the relative position data.

Finally, at step S180, the synchronized images are displayed, for example, on the display device 66, or on the display device 82 arranged in the pair of eye glasses 80. The physician or surgeon is thereby capable of positioning the patient in the treatment position using the super-positioned three-dimensional reference image as a guide. When the patient is aligned with the three-dimensional reference image, the patient is located in the correct treatment position.

Although an exemplary embodiment of the present invention has been shown and described, it will be apparent to those having ordinary skill in the art that a number of changes, modifications, or alterations to the inventions as described herein may be made. Thus, it is to be understood that the above description of the invention and the accompanying drawings is to be regarded as a non-limiting.

Claims

A system for projecting a three-dimensional image of a patient anatomy relative a therapeutic apparatus using augmented reality, comprising:

- a tracking and monitoring device configured to:

monitor said therapeutic apparatus and provide therapeutic apparatus position data, said therapeutic apparatus position data describing a position of said therapeutic apparatus in six dimensions relative said tracking and monitoring device; track an image recording device and providing image recording device position data, said image recording device position data describing a position of said image recording device in six dimensions relative said tracking and monitoring device;

- an image recording device configured to record images of said therapeutic apparatus, said images including at least the portion of said patient including the part being a subject for therapy;

- a processing unit configured to:

extract position data of the anatomy of said patient from said therapeutic apparatus, said position data defining a predetermined treatment position of said patient on a treatment surface for a therapy session relative said therapeutic apparatus;

create a three-dimensional reference image of said patient using said extracted patient position data;

super-position said three-dimensional reference image of said patient on said treatment surface, said three-dimensional reference image being positioned in said predetermined treatment position relative the therapeutic apparatus;

synchronize said super-positioned three- dimensional reference image and said recorded images using relative position data defining a relative position of the therapeutic apparatus to the image recording device; and

- a display device configured to display said synchronized images, wherein a user can be provided with guidance when positioning a patient relative said therapeutic apparatus for treatment session.

2. The system according to claim 1 , wherein said processing unit

comprises:

a patient position extraction module configured to extract said position data of the anatomy of said patient from said therapeutic apparatus, said position data defining a predetermined treatment position of said patient on a treatment surface for a therapy session relative said therapeutic apparatus;

a reference creating module configured to create said three- dimensional reference image of said patient using said extracted patient position data;

an image super-position module configured to super-position said three-dimensional reference image of said patient on said treatment surface, said three-dimensional reference image being positioned in said predetermined treatment position relative the therapeutic apparatus; and

an image synchronizing module configured to synchronize said super-positioned three-dimensional reference image and said recorded images using relative position data defining a relative position of the therapeutic apparatus to the image recording device.

3. The system according to claim 1 or 2, wherein said processing unit comprises a relative position data calculation module configured to calculate relative position data defining a position of the therapeutic apparatus relative the image recording device based on said therapeutic apparatus position data and said image recording device position data, said relative position data calculation module being configured to provide said relative position data to image synchronizing module.

The system according to claim 1 or 2, wherein said tracking and monitoring device comprises a relative position data calculation module configured to calculate relative position data defining a position of the therapeutic apparatus relative the image recording device based on said therapeutic apparatus position data and said image recording device position data, said relative position data calculation module being configured to provide said relative position data to image synchronizing module.

The system according to claim 1 - 4, wherein said tracking and monitoring device is a infra-red, IR, tracking and monitoring device comprising:

at least one IR light emitting module adapted to emit IR light; and

at least one IR light detector adapted to receive and detect IR light and to provide output signals corresponding to the detected IR light.

The system according to claim 5, including IR markers arranged to reflect IR light, wherein at least three markers are arranged non- linearly on said image recording device and at least three markers are arranged on said therapeutic apparatus or in vicinity of said therapeutic apparatus.

The system according to any one of preceding claims 1 - 4, wherein said tracking and monitoring device and said image recording device is a video camera.

8. The system according to claim 7, further comprising at least one

marker arranged on said therapeutic apparatus or in vicinity of said therapeutic apparatus and being arranged to be visually recognized by said video camera to allow said marker to be captured in said recorded images.

9. The system according to claim 1 - 8, wherein said display device and said image recording unit are integrated into a pair of glasses, said glasses including a head mounted display or heads-up display.

10. A method for projecting a three-dimensional image of a patient anatomy relative a therapeutic apparatus using augmented reality comprising:

creating said projection of said patient anatomy based on patient position data defining a predetermined treatment position relative said therapeutic apparatus, wherein said three-dimensional projection is used as a reference position of the patient;

obtaining a video-feed including at least a part of the therapeutic apparatus and said patient; and

superimposing said projection on said video-feed to display said projection and said patient.

1 1 .The according to claim 10, further comprising:

monitoring at least a part said therapeutic apparatus using a tracking and monitoring device and providing therapeutic apparatus position data, said therapeutic apparatus position data describing a position of said therapeutic apparatus in six dimensions relative said tracking and monitoring device;

tracking an image recording device using said tracking and monitoring device and providing image recording device position data, said image recording device position data describing a position of said image recording device in six dimension relative said tracking and monitoring device;

determining relative position data for said therapeutic apparatus relative said image recording device;

extracting patient position data of the anatomy of said patient, said position data defining a predetermined treatment position of said patient on a treatment surface for a therapy session relative said therapeutic apparatus;

recording images of said therapeutic apparatus using said image recording device, said images including at least the portion of said patient including the part being a subject for therapy;

creating a three-dimensional reference image of said patient using said extracted patient position data;

super-position said three-dimensional reference image of said patient on said treatment surface, said three-dimensional reference image being positioned in said predetermined treatment position relative the treatment appratus;

synchronizing said super-positioned three-dimensional reference image and said recorded images using said relative position data; and

displaying said synchronized images, wherein a user is provided with guidance when positioning a patient relative said therapeutic apparatus for treatment session.